This application claims the benefit of the Japanese Patent Application No. 2010-152338 filed on Jul. 2, 2010, the entirety of which is incorporated by reference.
1. Field of the Invention
The present invention relates to an oil pulse rotary tool that intermittently produces a large torque using an oil pulse generator.
2. Description of the Related Art
Japanese Patent No. 3653205 Publication discloses an oil pulse rotary tool that buffers an impact force produced by oil pressure of an oil pulse generator. According to the oil pulse rotary tool disclosed in Japanese Patent No. 3653205, when rotation speed of an output shaft of the oil pulse generator is reduced during screw tightening by a bit mounted to the output shaft, a ball retracts along a cam groove provided in a spindle of the speed reduction mechanism between the spindle and a hammer fitted on the spindle with play therebetween. As a result, the hammer retracts against an urging force of a coil spring, and the above impact force can be effectively buffered in accordance with the spring force of the coil spring.
In the above oil pulse rotary tool, the coil spring is provided between the speed reduction mechanism and the hammer which corresponds to a coupling body coupled to the speed reduction mechanism, in the axial direction of the spindle. Therefore, it is necessary to secure a space for arrangement of the coil spring between the speed reduction mechanism and the coupling body. Thus, an increase in the external dimensions of a housing to accommodate the coil spring causes an increase in the overall length of the oil pulse rotary tool including the housing.